1. Field
One or more embodiments of the present invention relate to an apparatus, method and medium outputting a wide gamut space image, and more particularly, to an apparatus, method and medium outputting a wide gamut space image in which one or more parameters that are needed to convert an existing color space into a wide gamut space are experimentally determined and then are applied to an input image.
2. Description of the Related Art
In order to meet various user demands, the functions of digital image devices such as monitors, scanners, or printers have diversified and have been improved. Digital image devices may adopt different color spaces or color models according to their intended use. Color models are classified into device-dependent color models and device-independent color models. Examples of the device-dependent color models include red-green-blue (RGB) models and cyan-magenta-yellow-black (CMYK) color models, which are a type of subtraction color space models. Examples of the device-independent color models include CIE color models such as a CIE LAB model, a CIE XYZ model, and a CIE LUV model.
The CIE L*a*b* model quantifies colors defined by the Commission Internationale de l'Eclairage using color space coordinates, and represents the results of the quantification as L* (lightness), a* (red-greenness), and b* (yellow-blueness). The CIE XYZ model represents a set of RGB tristimulus values as another set of tristimulus values that are all positive, i.e., X, Y, and Z values. The CMYK color space is commonly used in the field of printing, and the RGB color space is commonly used in various industrial fields that involve the use of computer monitors, such as the field of web graphics.
Digital imaging devices may output colors in an input image as they are, or may convert one of the colors in the input image and output an image obtained by the conversion, thereby enabling users to enjoy images with more natural colors.
In the meantime, a wide gamut space can be used to convert colors in an image into more natural ones. A wide gamut space is a color space having a wider range of colors than a standard RGB (sRGB) color space (IEC 61966-2.1) and enables the representation of images with more natural colors. In the past, wide gamut space images were typically only demanded by professionals in certain fields. Nowadays, with an increasing demand for image output devices such as cameras, monitors, and scanners that support a variety of wide gamut spaces, wide gamut spaces have attracted more public attention.
Digital images created by imaging devices such as cameras that support wide gamut spaces include a wider range of colors than digital images created by imaging devices that support the sRGB color space, and are thus clearer than digital images created by imaging devices that support the sRGB color space. However, conventional digital imaging devices process a digital image including wide gamut space information in the same manner as an sRGB image. Thus, an output image obtained by handling a wide gamut space image may not be able to properly display a wide gamut of colors.
Korean Patent Laid-Open Gazette No. 2003-038058 discloses an apparatus for extending the gamut of color devices which receives RGB color coordinates from a narrow gamut device, converts the received RGB color coordinates into lightness, chroma, and hue coordinates, extends color attributes such as lightness and chroma using a linear extension formula, preserves color attribute information obtained by the extension such that the color attribute information can be prevented from being outside the gamut of a wide gamut device, and outputs the result of the preservation. This apparatus, however, performs color conversion on input colors simply by creating a lookup table regarding lightness, chroma, and hue and linearly extending the lookup table. Thus, this apparatus may not be able to properly perform color conversion and provide colors that are suitable for the human eye.
Therefore, it is necessary to develop color correction techniques capable of extracting one or more feature differences between a wide gamut space and an existing gamut space and realizing colors for an output image that are almost indistinguishable from those actually perceived by users based on the feature differences.